DP900钢的成形性及预应变对烘烤硬化行为的影响

Formality and influence of pre-strain on bake hardening behavior of DP900 steel

对汽车结构件用DP900钢的成形极限图进行了测试和研究,并运用数学模型进行了预测分析。利用内耗仪和透射电子显微镜从微观角度研究了预应变对烘烤硬化值的影响。结果表明:DP900钢室温下的力学性能为屈服强度604 MPa,抗拉强度935 MPa,均匀伸长率达到14%,断后伸长率为19%。冲压成形过程中,成形极限FLD0为0.245,基于Hollomon方程建立的成形极限数学模型的预测误差在0.2%~13.5%,平均误差为5.87%。预应变量的大小对BH值有显著的影响。随预应变增大,BH值先升高后降低,预应变为7%时达到最高值45 MPa。内耗峰值变化趋势与BH值一致。

The forming limit diagram of DP900 steel for automotive structural components was tested and investigated,and the mathematical model was used for prediction analysis.The influence of pre-strain on bake hardening value was studied from the microscopic view by means of internal friction instrument and transmission electron microscopy.The results indicate that the mechanical properties of DP900 steel at room temperature are the yield strength of 604 MPa,the tensile strength of 935 MPa,the uniform elongation of 14%and the longation after fraction of 19%.The forming limit FLD 0 is 0.245 during the stamping process,and the prediction error of the mathematical model of forming limit based on the Hollomon equation is 0.2%-13.5% with an average error of 5.87%.The value of pre-strain has great influence on BH value.As the pre-strain increases,the BH value first increases and then decreases,reaching the highest value of 45 MPa with pre-strain of 7%.The variation trend of the peak value of internal friction is consistent with the BH value.